


Demon Child

by littleberd



Category: Ao no Exorcist | Blue Exorcist
Genre: AKA, AND EVERYONE NEEDS TO SEE HIM AS THE BEAUTIFUL LITTLE CINNAMONBUN THAT HE IS!, RIN NEEDS TO BE LOVED AS A CHILD AGAIN!!!, Rin is turned into a child, i had to do this atleast once in my latest lifetime, it had to be done
Language: English
Status: In-Progress
Published: 2016-09-25
Updated: 2018-08-10
Packaged: 2018-08-17 02:24:12
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 3,929
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8126809
Author URL: https://archiveofourown.org/users/littleberd/pseuds/littleberd
Summary: Rin remembers the years at the Monastery. When he had too much anger for everyone because no one understood why he was angry and a body that couldn't bottle it all in. He hurt other kids in his class because they hurt other kids. He tried being nice. He tried being a good boy. And he was, but nobody saw it that way. They only saw the little boy with big unnaturally blue eyes and tiny bloodied fists. "Why am I bad?""That kid is a Demon Child!"Rin looks up at Father, "Is it true? Am I a demon child?"******"Thank you... Dad..."





	1. Little Boy Blue

**Summary for the Chapter:**

> This is what happens when you watch inuyasha right after you finish binge watching Blue exorcist...
> 
> Terrible awesome angsty cute things... TTUTT~♥ I REGRET NOTHING! BECAUSE HONESTLY RIN AND YUKIO WILL ALWAYS NEED TO STILL SETTLE THINGS AND EVERYONE IN THE EXWIRE CLASS NEEDS TO GET INVOLVED AND GIVE RIN THE LOVE HE DESERVES!!!!

Rin twists around the black and icky appendage that grabs at him. His triumph grin turns into a yowl when his tail is snatched, tears brim in his eyes at the heady pain. He drops Kurikara, it splats into the thick mud below.

"RIN!" Yukio and Shiemi shout at the same time, Yukio is held back by more of the tendrils coming out of the monster, and Nii can't summon anymore plants without the risk of passing out. Bon and Konekomaru don't stutter in their chants in search of it's deadly verse, but their eyes are worried as they can only watch. Shura is surprisingly not here at the moment, having a rare summons to the Vatican to attend to along the side of Mephisto. Izumo is currently protecting Shiemi from attacks while Yukio is fending off any that go near his two students chanting away the book of Jacob. Shima isn't there because he's been summoned along with the Vatican group.

Rin is on his own.

Rin eyes the demon in front of him, it's apparently a demon that absorbs children. A type of ghoul that was made from mothers who lost their offspring to war and famine.

"You want your kid back so bad!? Then TAKE ME!" Rin's flames burn as blue as his eyes. The demon complies, in each azure blaze his life plays backwards. And each memory that appears in the those blue flames burns from his mind. His body, slowly shrinking, and de-aging.

The past is seen by all in the field of rice paddies. Rin has a brave face, filled with determination and his flames continue to burn brighter, the creature slowly fading and resembling a woman in shape.

But then... His last moments with Father Fujimoto Shiro plays out for him to see.

Rin releases a broken whimper, his face contorting into tears, his resolve utterly shattered. Yukio yells for his brother when Rin gives up. His transformation speeding up, the demon is very near human looking now.

Takara, who has been watching the battle from afar the entire time, pulls out a character doll, writes child in kanji on it in permanent marker, and tosses it at the demon. The voodoo doll brightens, and the motherly demon of sorrow drops Rin like a sack of molding potatoes. Bon manages to catch the 2-year-old version of Rin before his body can be devoured by the thick mud below.

The demon tenderly holds the doll and is slowly purified, a young woman who looks to have had the short end of the universal stick when she was alive, by the state of her peasant garbs, weeps in joy as she floats up into the sky, her light vanishing ever so slowly.

The True Cross Academy students gather around Bon, peering down at the toddler Okumura Rin as he fretfully shifts in Bon's arms.

A small sniffle escapes the pouting pink lips as his blue blue eyes look at each of the classmates around him, tearful and frightened.

"Daddy? Whe'e Daddy at? Yu-yu? Wh-whe'e d-daddy and yu-yu? W'-win scawed...p'omise won't be ba-bad 'gain...Win 'll be good boy p'-p'omise... Want-t daddy and yu-yu..." Rin mumbles before he passes out from exhaustion and stress of the entire ordeal, his demonic features stay as they were, his tail curls around himself in a pathetic attempt at self-comfort.

Bon looks to Yukio and the teacher gratefully takes the pitiful bundle, "I hope he returns to normal faster than I think Mephisto will say he will..."

_I will NOT be telling a toddler Rin that he killed Dad... His demon blood is active now too... This isn't going to be good. Hopefully this'll be over before the Vatican hears about it._


	2. 'little' big brother

Yukio stomps right into Mephisto's office without giving a single explanation to the other faculty staring at the seething normally calm teacher stampeding toward the demon headmaster's private room.

Yukio kicks the door open and shoots it shut, a wide eyed toddler Rin bundled in a blanket in his arms.

Mephisto raises an eyebrow but that's the only really expressive response he gets out of the old demon, who continues to stir his tea as nonchalant as usual.

"How do we turn him back?" Yukio asks, eyes narrowed, a small vein reveals itself on his forehead and beats in time with his ever increasing pulse.

"Calm yourself Mr. Okumura, you're far too young to die from high blood pressure but at this rate you're close to proving me wrong." Mephisto begrudges, Yukio's nose twitches but he stiffly takes a seat.

Rin bites his lip adorably and spots the big hat Mephisto has on. Eyes going wide in wonder Rin makes grabby hands at it, "C-can W-Win twy on?"

Both older men blink, but Mephisto catches on quickly, "Why yes, Win-win can try on big brother's hat. Just be careful little one, it's my favorite."

Mephisto hands it over to the small boy and Rin carefully holds it, gently putting it on his head and blocks Yukio's face from view with it's height.

Yukio huffs in annoyance but deposits his older-young brother on the ground. He wanders about the room, looking at everything but never touching.

"How do I turn Rin back to his actual age?" Yukio persists, view now unobstructed by the flamboyant top hat.

Mephisto watches Rin go about the room, inspecting everything and exploring, "Why do you want to turn him back so badly? Does the fact that he's a demon while in this younger form mess with your image of your big brother?"

Yukio is about to tell the demon right where he can shove that rhetoric when Rin gasps in surprise.

Yukio turns to look at Rin and sees him crowding a corner, Mephisto's eyes bug out and he's up in a flash, but too late.

Rin starts bawling his poor head off, clutching his finger that's bleeding slightly. Mephisto levitates the boy and magics a bandaid on withing a second and a half. 

"Sorry baby brother, but you shouldn't trap an animal you don't know in a corner like that, " Mephisto holds up the culprit by it's itty bitty scruff, the green hamster's tiny legs kicking with all it's might trying to get free, " Even tiny little hamsters like this one will seek to defend themselves against bigger creatures."

Rin nods his head but stutters, "W-wasn't trying to hu-hurt him. He was stuck behind da bookshe-shelf because he had too many seeds in his cheeks... Had to push them out, and-and once w-win did... He Bit me...*sniffle sniffle*"

Mephisto leered at the hamster which had stopped moving, breathing in heavy little huffs, it looked remorseful at that.

Rin put on a brave face, "But-but w-win learned his lesson! W-win won't do that no more. W-win didn't mean to scawe you, w-win sowwy."

Mephisto smiles softly at him, quickly placing the hamster in the shocked boy's hands, "It's not your fault in the slightest my boy, if anything you were being a perfect gentleman to this _rodent_. So as a treat you can hold him and pet him."

Rin delicately put a finger in front of the green fiend for it to sniff him, once to took a whiff Rin used the single finger to pet the little biter. The hamster rolled over and exposed his stomach, causing a cute giggle to tumble from the boy's grinning lips.

Mephisto watched as the boy and the hamster were soon playing together as if nothing had happened.

Mephisto turned to the fuming exorcist staring laser beams into his back, "There is no way to cure him but he will grow back to his own age far more quickly than he did his first time around, a week is equal to a year in his aging. And along with his aging his memories will come back as well."

Mephisto snatched the boy and levitated him around in a slow and large circle, "For now, just enjoy having a 'little' brother, it's the only chance you'll have, so make the most of this novelty for the time. That's all I can do for now. Take him to classes with you, for your test days Ukobach will babysit at your dorm."

Mephisto stopped for a moment, Rin fell into the demon king's arms with a squeal of delight, followed by little giggles, "oh! And before I forget!" Mephisto plucked his brooch from his coat, and pinned it over Rin's heart, "This'll keep those without a temptaint from seeing Win-win's more impishly handsome features from causing panic around campus.

Yukio quickly picked Rin up and speed walked to the door, Rin looked over his bigger brother's shoulder waving goodbye, " Bye-bye hamser Amom and Mephy! Mr. Whewe is Yu-yu and Daddy? You pwomised you would take me to them! Have to pwotect Yu-yu fwom those mean kids on the playgwound because they mean to him all the time because he's smawtew than them and they's jeawous."

Yukio laughs a bittersweet laugh, "It'll be a little longer Rin, Daddy's-Daddy and Yukio are on a trip. They went to talk to those kid's parents. They'll be back a long while though because they have to sit through one of his lectures."

Rin nods knowingly, "Daddy does like to talk to much. Especially when theiw momma's have big boobies."

Yukio nearly choked on that explanation, wiping tears from his eyes. _Only my Big Brother would say something like that... Even though it'd be true._


	3. Too Good To Be True

Yukio wasn't surprised when he returned to the dorms with Rin to find a bag of kid cloths in the middle of the floor, a note with "Mephisto" written in big elegant cursive on the front.

Rin was obedient and very solemn when addressing his bedtime duties. His scowl was adorable when he went to brushing his teeth in the mirror with such ferocity that the tooth paste was practically foam in his mouth. He carefully tucked in his tail when he pulled his blue star patterned pajama pants on, and he scrutinized the buttons with such focus a couple of practice candles that older-bodied Rin had left around in his pig sty area lit up and spluttered out with each button that went into it's designated hole or one below or above it. And finally, when Yukio had Rin tucked into the bottom bunk and had turned off the light, he heard Rin do something he had stopped doing right around their last year in primary school... Rin was praying.

"Oh lowd, pweaze pwotect yu-yu and daddy while they'we talkin to da buwwies momma's. Pweaze tell da buwwies momma's not to hit daddy too hawd because he's jus teasin and he jus likes big boobies cuz they'we soft like pillows. Pweaze tell da buwwies to STAWP and make them be nice to yu-yu cuz he jus wantsa be fweinds wif them. Gawd, if you can do that and you still have time left over... Can you give yu-yu some of my courage? I'm a big bwothew but yu-yu needs to feel what it's like to stand up four himself... I'll always pwotect him but when I can't, pweaze give him da stwength you gave me. And becuz daddy made me pwomise to aakythis can you pweaze give him a pretty lady wif big boobiez that won't hit him? Ahmen."

Yukio had to bite his lip to stop himself from laughing, honestly he couldn't help but think of Rin as adorable like this. Rin would always put his heart and soul into it, whatever he did he always did try.

Once Rin's breathing evened out and soft snores could be heard, Yukio closed his book, and turned the lamp light off.

Before going to bed he kissed his big brother's crown, "Night big brother."

***************

Getting Rin up on the other hand held the same reaction as chalk on a chalk board. Yukio was nearly late because he had to literally drag his older brother out of bed and wrestle cloths on him. Ukobach was of a little help but only because Rin was completely convinced the kitchen demon was actually one of Santa's elves, and was too enthralled by him to fuss about eating.

When Yukio finally made it to class the door nearly took his arm off when It was slammed shut on his upper arm. He knew he'd be sporting bruises there within the hour. But the teacher's disgruntled glare at Yukio's save quickly turned to surprise when he saw Yukio with a little boy in his arms.

"Oh, so you're the student who is bringing their relative to class. The headmaster informed me of the details but didn't exactly say who it was." Mr. Toya establishes, prying the door out of the student body president's arm. Mr. Toya had made it clear from the beginning that he hated any student that got straight A's through high school, Yukio had been subjected to a lot of rude comments by this teacher since the moment he stepped into the classroom. 

But by the looks of his practically cuuing eyes at Rin, he had a soft spot for children. Yukio carried Rin all the way to his desk and a fangirl of his pulled out a chair for the little tyke. Rin grinned at the girl and said 'tank youu big siswer'. The female half of the class along with the teacher and a few mature boys melted on the spot.

Before the lesson began Yukio procured a coloring book and a box of crayons to occupy his time. But half way through the history lesson over the beginning half of the Edo period rin excitedly tugged at Yukio's uniform sleeve. Yukio hesitantly pulled himself away from the nap-worthy lecture.

Rin points at Bon that's a few desks down and, in complete hero-worshipping awe, yells "Mr.! It's Yugi Muto!" 

This wakes up a third of the class, and the rest are stifling snickers or out right laughing. Mr. Toya is coughing uncontrollably from the front of the classroom.

And Ryuji Suguro is torn between glaring the kid down and blushing in embarrassment. But even he can't escape the imp's charm, Rin's shining eyes never leave the kid of the cursed temple. Bon can't help but be bashful about the star-struck gaze little Rin is giving him. A small chuckle releaves his tension, and Bon smiles back at him.

After that event the rest of the day goes pleasantly the same, a few more nicknames are given to students and teacher's who stand out... Professor Tsubaki's was going to stick for the rest of his career at true cross if Yukio had any say because professor Alexander Cabot III was too good a match. 

And once regular classes are over Yukio drops Rin off with Ukobach who's excited as Rin is by all appearances. Ukobach was planning on teaching Rin different cooking dishes that a child could do without danger, Mephisto was even there to make sure of that.

But the fact Mephisto is alone with a toddler Rin does not rest easy on Yukio's mind; therefore, Yukio takes his class on a field trip to the empty lot of land behind the dorm to observe the native wild demons that inhabit the area.

It seems his suspicion is slightly correct because there are no native wild demons there... Because two demon kings miasmas scared the wildlife away. And little Rin is being tossed in the air by the Demon King of Earth, Amaimon... Who, not even a month ago, had tried to kill Rin.


	4. Done Screwed Up Didn't I?

Yukio shoves his glasses up the bridge of his nose so hard he feels his skin turn red from the burn.

"Class, report back to the exorcist classroom and read through chapters fifteen through eighteen. There are important medicines dealing with the damages holy water soaked bullets can do to demons I want you to pay _particular_ attention to." Yukio addresses his class. His students see the blood vessel nearly popping out of their teacher's forehead and wisely follow his orders, packing up their stuff and walking away from the strange scene.

Once they're out of sight Yukio doesn't hold back. Rin tugs on his younger brother's sleeve with tears pouring down gis face. By the end of the fight Amaimon and Mephisto are sporting several severe wounds and are sitting on their knees in shame as Yukio chews them a new one.

"THROWING A YOUNG CHILD IN THE AIR COULD HURT THEM! AND NO MEPHISTO! IT DOESN'T MATTER IF YOU SWEAR YOU'LL CATCH HIM EVERYTIME! HE COULD BE CAUGHT WRONG AND GET A SPRAIN! FOR DEMON KINGS THAT REIGN OVER VAST TERRITORIES IN HELL YOU TWO DON'T KNOW THE FIRST THING ABOUT CHILDREN YOU MORONS!"

Once his rant is done he looks at Rin... Only to find that he is no longer there, salty drops of water on his sleeve leave him feeling much worse.

"I've screwed up haven't I?"

"Yes," Amaimon states bluntly, Mephisto whacks him on the back of his head.

"That was rhetorical little brother."

"I know, I'm a demon, I live to make humans uncomfortable." Amaimon replies back, Mephisto pinches his nose, feeling the oncoming migraine.

"I believe you're confusing the word uncomfortable with annoying." Mephisto sighs.

Yukio tilts both demon king's heads up with the business ends of his handguns, "Forget what you lived for before, now your one purpose in life is finding Rin, and he better be SAFE and SOUND when I get back. Because I have an unlimited ammunitions gift card and a steady supply of holy water, not to mention the fact I know every pressure point on your damned bodies that could leave you in misery for years. So I suggest you get to it."

Yukio flicks the guns, earning a red mark on both of their chins, and deposits his weapons back in their holsters. He makes his way to the exorcist classrooms and can't help but worry even more over Rin.

_What have I done now?_


	5. Chick Magnet

**Summary for the Chapter:**

> The title is the biggest hint I could ever possibly give you lmfao.  
> Sorry for the long wait guys but I'm BACK BABY!

Rin didn't care where he ran, he couldn't really see anything anyway with his tears blurring street signs and houses. When he finally did stop running he looked around and found himself at a complete loss as to where he was. It was a rather dark crossing in between buildings, the alleyways were littered with trash and garbage bags ad broken bottles. He sniffed and rubbed his eyes and snotting nose on his purple and orange striped shirt sleeve. 

"Y-you gotta find a gwon-up when you-u get wost... dats what daddy told me and yu-yu... Bu-but I don' see any gwon-ups anywhewe..." Rin sniffles, hugging himself and shaking.

A familiar boy walks around a corner, glances over, and then does a double take, "RIN!?!" Shima blinks and quickly kneels down in front of the teary-eyed little boy, "What are you doing here?" Shima scanned his surroundings warily, "Where's your brother?"

Rin burst into a new flood of tears, "I DON'T KNOW WHEWE YU-YU AND DADDY AWE *SOB*!!! THAT MISTEW WAS SUPPOSED TO TAKE ME TO DEM BUT HE LIED*SOB*!!! AND*sniff*-AND*sniff*-AND*sniff*!!! HE YELLED AT UNK-MEPHY AND AMOM!!! THEY WAS JUST PWAYIN WIF ME CUZ UKO-SAN WAS-WAS WAITIN FOW DA CAKE TO GET DONE BECUZ I BAKED IT FOW MISTEW WHEN HE GOT BACK FWOM WOWKING!!! *SOB* DEN I GOT WOST AND*sniff*-AND*sniff*-AND*sniff* I DON' KNOW HOW TO GET BAC-*sob* I WAN' MY DADDY AND YU-YU!!!!!"

Shima looks around frantically, not knowing a THING about how to handle kids, so the only thing he can think of is to pat his back. Rin helps him in this regard, by latching on Koala-style and his new wave of snot dribbles onto his shirt. Shima cringes at the slimy feeling but deals with it. Bugs? Out of the question. Snot? Gross but manageable. Shima picks the boy up, resting Rin's bottom on his arm and hugging him close.

"How about we go get some ice cream and let you cool down. And once we do that I can take you back alright? Maybe we could even stop by the park to play, would that be ok?" Shima tries, Rin nods into Shima's shoulder, refusing to let go as his little body quaked but still calming down with little sniffles and huffs into the fabric.

Shima doesn't smile, really, he _doesn't_ his lips just twitched a little bit from the kid's lukewarm fluids leaking through his shirt and meeting his skin with a chill.

***************

Rin's demeanor changes as soon as he sees the playground. Blue puffy eyes gleaming in excitement rather than from fresh tears. He practically jumps out of Shima's arms. Once his little feet hit the ground he's gunning it for the only open swing.

"Pinky! Pinky! COME PUSH ME!!" Rin yells giddily, Shima starts trudging over begrudgingly, eye twitching at the new nickname, but then he sees the eyes on the bright little demon boy. About three baby sitters are cuuing at Rin's enthusiasm whilst their babbling infant charges are looking at the sand like it's a living organism. Something in Shima's brain clicks as he looks between Rin and the baby sitters.

"Rin you beautiful wing-man in the making, I hope you never grow up." Shima whispers to himself as he rushes over from the little distance he was from the boy.

"Hyer! Hyer! Pinky! You awe weally wimpy! Daddy ca-can make me do fwips over da bar!" Rin blubbers, and his happy cries take a 180 degree right curve, turning into pitiful little hiccups when he accidentally reminds himself that his 'Daddy' isn't here.

The girls blink at this, half look at Rin with a pitiful pout while the others lose interest seeing as they already have a squalling baby they were paid to take care of.

Shima swoops Rin out of the swing and holds him upside down, "Turn that frown upside down Rin, you'll see 'em soon. I'm sure of it." Rin starts giggling at the angle and Shima hauls him back right-side up. "Anyway, let's go get some ice cream, yeah? What flavor's your favorite?"

Rin's smile brightens even more as he goes into great detail of what exactly is the greatest ice cream flavor and why.

Shima only comments every so often to make it seem like he's paying attention but his eyes dart every so often back to the group of babysitters. Shima quickly ushers Rin over to a bench next to the largest group of babysitters.

Rins eyes squint as he looks away from his raspberry blue Popsicle when he hears a giggle from one of them and sees a pretty brunette waving at Shima. Rin grins mischievously, "Hey! Pwetty Waidy! Pinky said he wikes youw boobiezzzz!"

Five minutes later Yukio is opening the door only to be met by the sight of a bright red hand-print taking up residence on Shima's cheek.

"Um.. Shima what happe-"

Shima shoves a struggling Rin into Yukio's chest, "Trust is a fragile thing with silk feathers... and Rin's? His is dead to me. Good day Teach. And a word of advice, teach him to be a better wingman."

Yukio closes the door slowly as he looks down at the cackling little half-demon, "We're going to have a grown-up talk about how irresponsible running away without telling an adult where you're going is... but first... what did you do to have Shima slapped?"

Rin shakes his head, "He waz haven' dirty thouwts wike Daddy cuz he waz wookin at girlz boobiez."


End file.
